1. Field of the Invention
The present invention is generally related to a type of electrical contacts, and more particularly, to a type of electrical contacts used in card connectors, battery connectors or board to board connectors.
2. Description of Related Art
A variety of electrical connectors are widely used in electronic devices for transmitting signals between them. Electrical connectors each comprise a plurality of electrical contacts for contacting with electrical elements of a complementary connector. For achieving reliable and continuous signals between the electronic devices, the electrical contact must be applied with adequate normal force when the electrical connector with the electrical contacts assembled mates with the complementary connector. Inadequate normal force between the electrical contacts and electrical elements of the complementary connector easily causes signal instability.
U.S. Pat. No. 5,971,809 (the '809 patent) discloses a conventional electrical connector. Referring to FIG. 4 adapted from FIG. 2(A) of the '809 patent, the connector 1 includes an insulated housing 10 and a plurality of first electrical contacts 110 and second electrical contacts 111. The housing 10 comprises a plurality of passageways 1011 in which the first and the second electrical contacts 110, 111 respectively are secured and a plurality of protrusions respectively formed in corresponding passageways. Each electrical contact comprises a mating portion 1101 for electrically contacting with electrical element of a complementary connector, a preload portion 1104 extending forwardly from the mating portion to abut against corresponding protrusion of the housing, a solder portion 1103 for connecting the connector with a printed circuit board and a retention portion 1102 between the mating portion and the solder portion for securing the electrical contact to corresponding passageway of the housing. The second electrical contact comprises a mating portion 1111 for electrically contacting with the electrical element of the complementary connector, a preload portion 1114 extending forwardly from the mating portion to abut against corresponding protrusion, a retention portion 1112 and a solder portion 1113 extending rearwardly from the retention portion. The mating portions of the first and the second electrical contacts are pressed to deform elastically by normal force occurred when the electrical connector is engaging with the complementary connector. The first and the second electrical connector respectively comprise a preload portion which prearranged some elastic deformation to the first and the second electrical contacts. Thus, the normal force applied on the electrical contacts is equivalent to the normal force added by the prearranged elastic deformation and the actual elastic deformation.
However, with the development toward miniaturization and integration of the electronic devices, the electrical connector not only become more and more smaller than before but also required to transmitting signal more stably. This trend of development induces that the electrical contacts should be loaded by adequate normal force. After the electrical connector connecting or disconnecting with its complementary connectors several times, electrical contacts are pressed by the normal force between the electrical contacts and electrical elements of the complementary connector to offset from its correct positions. Thus, the configuration of the conventional electrical connector cannot fulfill the requirement of providing adequate normal force on the electrical contacts.
Hence, an improved type of electrical contacts is highly desired to overcome the aforementioned disadvantages of the prior art.